The present invention relates to a printer which has a traveling print head.
The present invention relates more particularly to a carriage position control system in a printer having a traveling print head or a carriage such as an ink jet system printer or a thermal printer.
The present invention will be described in conjunction with an ink jet system printer.
In general, in an ink jet system printer, a carriage is driven to travel in a reciprocating mode with respect to a recording paper to perform a desired printing. When the ink jet system printer is used as an input device or an intermittent mode printer, the carriage must intermittently travel in response to an input signal from a suitable input unit such as a keyboard. The intermittent travel is achieved by provision of a servomotor for driving the carriage to travel at a predetermined length of distance in response to the input signal. In this intermittent mode, the carriage must be held stationary at a predetermined position and driven to travel at a predetermined length of distance in response to the input signal and thereafter held stationary at a next predetermined position.
The position of the carriage can be detected with the use of a disc having slits mounted on the shaft of the servomotor. When the carriage is controlled to stop at a predetermined position with the use of an optical system including the slit disc, the standstill position may unavoidably vary. This variation is caused by the variation of characteristics of electronic elements used in the optical system dependent upon the temperature or caused by the variation of the rotation angle of the servomotor till a print termination signal is generated.
The variation of the standstill position of the carriage may preclude a clean printing.